import java.util.HashSet;
import java.util.Scanner;

public class Test {
    //字符串去重
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String str = scanner.nextLine();
        scanner.close();
        HashSet<Character> hs = new HashSet<>();

        //write your code here......
        for(int i = 0;i < str.length();i++){
            char ch = str.charAt(i);//Set中只存储了key,并且要求key一定要唯一
                hs.add(ch);
        }
        for (char c:hs) {
            System.out.print(c);
        }
    }
}
